Partial-volume effect on ischemic tissue-fate delineation using quantitative perfusion and diffusion imaging on a rat...

Area of Science:

• Neuroimaging
• Biomedical Engineering
• Stroke Research

Background:

• Partial-volume effects (PVE) in medical imaging, particularly in stroke, can obscure accurate tissue classification.
• Distinguishing between normal, ischemic, and at-risk tissues is critical for effective stroke management.

Purpose of the Study:

• To investigate the impact of partial-volume effects on tissue classification in focal ischemia using high-resolution (HR) and low-resolution (LR) imaging.
• To quantify misclassified pixels due to PVE and assess its progression with ischemia.

Main Methods:

• Cerebral blood flow (CBF) and apparent diffusion coefficient (ADC) were measured in rats with focal ischemia at HR (128x128) and LR (64x64) resolutions.
• Pixel-by-pixel analysis was performed to evaluate PVE and misclassified tissues.
• High-resolution data were degraded to lower matrices, and low-resolution data were zero-filled to assess PVE severity.

Main Results:

• Significant ischemia-related PVE was observed in ADC and CBF maps at the boundaries between normal and abnormal tissues.
• PVE misclassified substantial pixels, overestimating abnormal volumes at the expense of at-risk and normal tissues.
• PVE severity increased with decreasing resolution and was more pronounced at early time points post-ischemia.

Conclusions:

• Partial-volume effects significantly confound the accurate delineation of ischemic tissues in stroke imaging.
• PVE severity is dependent on image resolution and timing post-ischemia.
• These findings highlight the challenges PVE poses for interpreting the ischemic penumbra and guiding therapeutic interventions.